Background

This PR is specific to the macOS app under macOS/WritingTools. Other platform implementations live in separate codebases and are not affected.

The macOS app currently opens Privacy & Security settings with URLs using the x-apple.systemsettings scheme, for example:

x-apple.systemsettings:com.apple.settings.PrivacySecurity.extension?Privacy_Accessibility

On macOS 26.4 (25E246), that scheme has no registered handler, which causes macOS to show:

There is no application set to open the URL ...

This appears to be a regression introduced by switching from the old x-apple.systempreferences scheme to x-apple.systemsettings. Although Apple's settings app is now named System Settings, its bundle identifier and URL scheme still use the older System Preferences naming.

Investigation

I checked the local System Settings app metadata on macOS 26.4:

• /System/Applications/System Settings.app has bundle identifier com.apple.systempreferences.
• Its CFBundleURLTypes advertise x-apple.systempreferences.
• It does not advertise x-apple.systemsettings.

I also checked Launch Services through NSWorkspace.urlForApplication(toOpen:):

• x-apple.systemsettings:com.apple.settings.PrivacySecurity.extension?Privacy_Accessibility resolves to no handler.
• x-apple.systempreferences:com.apple.settings.PrivacySecurity.extension?Privacy_Accessibility resolves to /System/Applications/System Settings.app.
• x-apple.systempreferences:com.apple.preference.security?Privacy_Accessibility also resolves to /System/Applications/System Settings.app.

The Privacy & Security settings extension is still present as com.apple.settings.PrivacySecurity.extension, and its metadata includes allowsXAppleSystemPreferencesURLScheme = 1 plus legacy bundle identifier com.apple.preference.security. So the current extension identifier is valid, but it still needs to be opened through the x-apple.systempreferences scheme.

Repository history shows the current upstream x-apple.systemsettings URLs were introduced in commit 460f53f, replacing previously used x-apple.systempreferences:com.apple.preference.security... URLs.

Summary

• Replace the unsupported x-apple.systemsettings scheme with the x-apple.systempreferences scheme that System Settings actually registers.
• Try the current Privacy & Security extension identifier first.
• Fall back to the legacy Security preference pane identifier.
• Fall back to opening System Settings directly if deep linking fails.
• Refresh onboarding permission status when the macOS app becomes active again after the user returns from System Settings.

Testing

• Verified URL handler resolution locally on macOS 26.4 with NSWorkspace.urlForApplication(toOpen:).
• Verified the System Settings app bundle metadata locally: bundle identifier com.apple.systempreferences; registered scheme x-apple.systempreferences.
• Built the PR branch successfully with xcodebuild -project macOS/WritingTools.xcodeproj -scheme WritingTools -configuration Debug -destination 'platform=macOS' CODE_SIGNING_ALLOWED=NO COMPILER_INDEX_STORE_ENABLE=NO build.